<!DOCTYPE html>
<html>
<head>
  <title>Bootstrap 实例</title>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="stylesheet" href="https://cdn.bootcss.com/bootstrap/4.0.0-beta/css/bootstrap.min.css">
  <script src="https://cdn.bootcss.com/jquery/3.2.1/jquery.min.js"></script>
  <script src="https://cdn.bootcss.com/popper.js/1.12.5/umd/popper.min.js"></script>
  <script src="https://cdn.bootcss.com/bootstrap/4.0.0-beta/js/bootstrap.min.js"></script>
  <style>
  body {
      position: relative;
  }
  ul.nav-pills {
      top: 20px;
      position: fixed;
  }
  div.col-8 div {
      height: 500px;
  }
  </style>
</head>
<body data-spy="scroll" data-target="#myScrollspy" data-offset="1">

<div class="container-fluid">
  <div class="row">
    <nav class="col-sm-3 col-4" id="myScrollspy">
      <ul class="nav nav-pills flex-column">
        <li class="nav-item">
          <a class="nav-link active" href="#section1">Section 1</a>
        </li>
        <li class="nav-item">
          <a class="nav-link" href="#section2">Section 2</a>
        </li>
        <li class="nav-item">
          <a class="nav-link" href="#section3">Section 3</a>
        </li>
        <li class="nav-item dropdown">
          <a class="nav-link dropdown-toggle" data-toggle="dropdown" href="#">Section 4</a>
          <div class="dropdown-menu">
            <a class="dropdown-item" href="#section41">Link 1</a>
            <a class="dropdown-item" href="#section42">Link 2</a>
          </div>
        </li>
      </ul>
    </nav>
    <div class="col-sm-9 col-8">
      <div id="section1" c>    
        <h1>Section 1</h1>
        <p>Try to scroll this section and look at the navigation list while scrolling!</p>
      </div>
      <div id="section2" > 
        <h1>Section 2</h1>
        <p>Try to scroll this section and look at the navigation list while scrolling!</p>
      </div>        
      <div id="section3" >         
        <h1>Section 3</h1>
        <p>Try to scroll this section and look at the navigation list while scrolling!</p>
      </div>
      <div id="section41" >         
        <h1>Section 4-1</h1>
        <p>Try to scroll this section and look at the navigation list while scrolling!</p>
      </div>      
      <div id="section42" class="bg-info">         
        <h1>Section 4-2</h1>
        <p>Try to scroll this section and look at the navigation list while scrolling!</p>
      </div>
    </div>
  </div>
</div>

</body>
</html>